The evolution of pebble size and shape in space and time

We propose a mathematical model which suggests that the two main geological observations about shingle beaches, i.e. the emergence of predominant pebble size ratios and strong segregation by size are interrelated. Our model is a based on a system of ODEs called the box equations, describing the evolution of pebble ratios. We derive these ODEs as a heuristic approximation of Bloore's PDE describing collisional abrasion. While representing a radical simplification of the latter, our system admits the inclusion of additional terms related to frictional abrasion. We show that nontrivial attractors (corresponding to predominant pebble size ratios) only exist in the presence of friction. By interpreting our equations as a Markov process, we illustrate by direct simulation that these attractors may only stabilized by the ongoing segregation process.Comment: 22 pages, 8 figure

TMEDA in Iron‐Catalyzed Hydromagnesiation: Formation of Iron(II)‐Alkyl Species for Controlled Reduction to Alkene‐Stabilized Iron(0)

N,N,N’,N’‐Tetramethylethylenediamine (TMEDA) has been one of the most prevalent and successful additives used in iron‐catalysis, finding application in reactions as diverse as cross‐coupling, C‐H activation and borylation. However, the role that TMEDA plays in these reactions remains largely undefined. Herein, studying the iron‐catalyzed hydromagnesiation of styrene derivatives using TMEDA has provided molecular‐level insight into the role of TMEDA in achieving effective catalysis. Key is the initial formation of TMEDA‐iron(II) alkyl species which undergo a controlled reduction to selectively form catalytically active styrene‐stabilized iron(0)‐alkyl complexes. While TMEDA is not bound to the catalytically active species, these active iron(0) complexes cannot be accessed in the absence of TMEDA. This mode of action, allowing for controlled reduction and access to iron(0) species, represents a new paradigm for the role of this important reaction additive in iron catalysis

Provinciality and the Art World: The Midland Group 1961- 1977

This paper takes as its focus the Midland Group Gallery in order to first, make a case for the consideration of the geographies of art galleries. Second, highlight the importance of galleries in the context of cultural geographies of the sixties. Third, discuss the role of provinciality in the operation of art worlds. In so doing it explicates one set of geographies surrounding the gallery – those of the local, regional and international networks that connected to produce art works and art space. It reveals how the interactions between places and practices outside of metropolitan and regional hierarchies provides a more nuanced insight into how art worlds operated during the sixties, a period of growing internationalism of art, and how contested definitions of the provincial played an integral role in this. The paper charts the operations of the Midland Group Gallery and the spaces that it occupied to demonstrate how it was representative of a post-war discourse of provincialism and a corresponding re-evaluation of regional cultural activity

Ecological drivers of global gradients in avian dispersal inferred from wing morphology

An organism’s ability to disperse influences many fundamental processes, from speciation and geographical range expansion to community assembly. However, the patterns and underlying drivers of variation in dispersal across species remain unclear, partly because standardised estimates of dispersal ability are rarely available. Here we present a global dataset of avian hand-wing index (HWI), an estimate of wing shape widely adopted as a proxy for dispersal ability in birds. We show that HWI is correlated with geography and ecology across 10,338 (>99%) species, increasing at higher latitudes and with migration, and decreasing with territoriality. After controlling for these effects, the strongest predictor of HWI is temperature variability (seasonality), with secondary effects of diet and habitat type. Finally, we also show that HWI is a strong predictor of geographical range size. Our analyses reveal a prominent latitudinal gradient in HWI shaped by a combination of environmental and behavioural factors, and also provide a global index of avian dispersal ability for use in community ecology, macroecology, and macroevolution

Luck and tactics in foraging success: the case of the imperial shag

It has been proposed that predators searching for prey acquire food according to a probabilistic framework, where success is based on ‘luck’ and the odds of success vary with prey abundance. If true, this has major ramifications for variation in the rates of energy acquisition within animal populations, which is particularly pertinent in offspring provisioning and breeding success, because smaller animals (the young) cannot starve for as long as the adults. However, despite much general speculation about rates of food acquisition, no study has measured whether food encounter is probabilistic in wild animals. We used animal-mounted cameras to document all prey captures by wild imperial shags Leucocarbo atriceps as they hunted underwater and show that, although they mostly do not have inter-prey acquisition time distributions that accord with a ‘luck-based’ framework assuming a constant probability of finding prey over time, there is no difference in the predicted amount of food captured between models that use the empirical data or theoretical Poisson-based fits of the data. We also noted considerable inter-individual differences in foraging success that far exceeded any differences between empirical and theoretical inter-prey acquisition time distributions. The data were used in a probabilistic foraging model that made explicit the mechanistic link between random prey encounters and food-dependent breeding success, indicating that ‘less lucky’ individuals could not provision their broods at rates commensurate with normal growth while the ‘lucky’ birds could do so easily. Given the nature of food encounter in these birds, coupled with substantial inter-individual variation in foraging success, we suggest that more successful individuals are particularly choosey about when, how and where to forage, which results in them operating with higher odds of success

Priority areas for vulture conservation in the Horn of Africa largely fall outside the protected area network

Vulture populations are in severe decline across Africa and prioritization of geographic areas for their conservation is urgently needed. To do so, we compiled three independent datasets on vulture occurrence from road-surveys, GPS-tracking, and citizen science (eBird), and used maximum entropy to build ensemble species distribution models (SDMs). We then identified spatial vulture conservation priorities in Ethiopia, a stronghold for vultures in Africa, while accounting for uncertainty in our predictions. We were able to build robust distribution models for five vulture species across the entirety of Ethiopia, including three Critically Endangered, one Endangered, and one Near Threatened species. We show that priorities occur in the highlands of Ethiopia, which provide particularly important habitat for Bearded Gypaetus barbatus, Hooded Necrosyrtes monachus, Ruppell's Gyps ruppelli and White-backed Gyps africanus Vultures, as well as the lowlands of north-eastern Ethiopia, which are particularly valuable for the Egyptian Vulture Neophron percnopterus. One-third of the core distribution of the Egyptian Vulture was protected, followed by the White-backed Vulture at one-sixth, and all other species at one-tenth. Overall, only about one-fifth of vulture priority areas were protected. Given that there is limited protection of priority areas and that vultures range widely, we argue that measures of broad spatial and legislative scope will be necessary to address drivers of vulture declines, including poisoning, energy infrastructure, and climate change, while considering the local social context and aiding sustainable development.Peer reviewe

Luck in Food Finding Affects Individual Performance and Population Trajectories

Energy harvesting by animals is important because it provides the power needed for all metabolic processes. Beyond this, efficient food-finding enhances individual fitness [1] and population viability [2], although rates of energy accumulation are affected by the environment and food distribution. Typically, differences between individuals in the rate of food acquisition are attributed to varying competencies [3] even though food encounter rates are known to be probabilistic [4]. We used animal-attached technology to quantify food intake in four disparate free-living vertebrates (condors, cheetahs, penguins and sheep) and found that inter-individual variability depended critically on the probability of food encounter. We modelled this to reveal that animals taking rarer food, such as apex predators and scavengers, are particularly susceptible to breeding failure because this variability results in larger proportions of the population failing to accrue the necessary resources for their young before they starve, and because even small changes in food abundance can affect this variability disproportionately. A test of our model on wild animals indicated why Magellanic penguins have a stable population while the congeneric African penguin population has declined for decades. We suggest that such models predicting probabilistic ruin can help predict the fortunes of species operating under globally changing conditions

‘Triple wins’ or ‘triple faults’? Analysing the equity implications of policy discourses on climate-smart agriculture (CSA)

This paper analyses contrasting discourses of ‘climate-smart agriculture’ (CSA) for their implications on control over and access to changing resources in agriculture. One of the principal areas of contestation around CSA relates to equity, including who wins and who loses, who is able to participate, and whose knowledge and perspectives count in the process. Yet to date, the equity implications of CSA remain an under-researched area. We apply an equity framework centred on procedure, distribution and recognition, to four different discourses. Depending on which discourses are mobilised, the analysis helps to illuminate: (1) how CSA may transfer the burden of responsibility for climate change mitigation to marginalised producers and resource managers (distributive equity); (2) how CSA discourses generally fail to confront entrenched power relations that may constrain or block the emergence of more ‘pro-poor’ forms of agricultural development, adaptation to climate change, or carbon sequestration and storage (procedural equity); (3) how CSA discourses can have tangible implications for the bargaining power of the poorest and most vulnerable groups (recognition). The paper contributes to work showing the need for deeper acknowledgement of the political nature of the transformations necessary to address the challenges caused by a changing climate for the agricultural sector

Transforming Last-Mile Logistics: Opportunities for more Sustainable Deliveries

Road congestion, air pollution and sustainability are increasingly important in major cities. We look to understand how last-mile deliveries in the parcel sector are impacting our roads. Using formative field work and quantitative analysis of consignment manifests and location data, we identify how the effectiveness of life-style couriers is contributing to both environmental and non-environmental externalities. This paper presents an analysis of delivery performances and practices in last-mile logistics in central London, quantifying the impacts differing levels of experience have on overall round efficiency. We identify eleven key opportunities for technological support for last-mile parcel deliveries that could contribute to both driver eectiveness and sustainability. We finish by examining how HCI can lead to improved environmental and social justice by re-considering and realizing future collaborative visions in last-mile logistics

AVONET: Morphological, ecological and geographical data for all birds

Functional traits offer a rich quantitative framework for developing and testing theories in evolutionary biology, ecology and ecosystem science. However, the potential of functional traits to drive theoretical advances and refine models of global change can only be fully realised when species-level information is complete. Here we present the AVONET dataset containing comprehensive functional trait data for all birds, including six ecological variables, 11 continuous morphological traits, and information on range size and location. Raw morphological measurements are presented from 90,020 individuals of 11,009 extant bird species sampled from 181 countries. These data are also summarised as species averages in three taxonomic formats, allowing integration with a global phylogeny, geographical range maps, IUCN Red List data and the eBird citizen science database. The AVONET dataset provides the most detailed picture of continuous trait variation for any major radiation of organisms, offering a global template for testing hypotheses and exploring the evolutionary origins, structure and functioning of biodiversity.Fil: Tobias, Joseph A.. Imperial College London; Reino Unido. University of Oxford; Reino UnidoFil: Sheard, Catherine. University of Oxford; Reino Unido. University of Bristol; Reino UnidoFil: Pigot, Alex L.. University of Oxford; Reino Unido. University College London; Estados UnidosFil: Devenish, Adam J. M.. Imperial College London; Reino UnidoFil: Yang, Jingyi. Imperial College London; Reino UnidoFil: Sayol, Ferran. University College London; Estados UnidosFil: Neate Clegg, Montague H. C.. University of Oxford; Reino Unido. University of Utah; Estados UnidosFil: Alioravainen, Nico. University of Oxford; Reino Unido. Natural Resources Institute Finland; FinlandiaFil: Weeks, Thomas L.. Imperial College London; Reino Unido. Natural History Museum; Reino UnidoFil: Barber, Robert A.. Imperial College London; Reino UnidoFil: Walkden, Patrick A.. Imperial College London; Reino Unido. Natural History Museum; Reino UnidoFil: MacGregor, Hannah E. A.. University of Oxford; Reino Unido. University of Bristol; Reino UnidoFil: Jones, Samuel E. I.. University of Oxford; Reino Unido. University of London; Reino UnidoFil: Vincent, Claire. Organización de Las Naciones Unidas; ArgentinaFil: Phillips, Anna G.. Senckenberg Biodiversity And Climate Research Centre; AlemaniaFil: Marples, Nicola M.. Trinity College; Estados UnidosFil: Montaño Centellas, Flavia A.. Universidad Mayor de San Andrés; Bolivia. University of Florida; Estados UnidosFil: Leandro Silva, Victor. Universidade Federal de Pernambuco; BrasilFil: Claramunt, Santiago. University of Toronto; Canadá. Royal Ontario Museum; CanadáFil: Darski, Bianca. Universidade Federal do Rio Grande do Sul; BrasilFil: Freeman, Benjamin G.. University of British Columbia; CanadáFil: Bregman, Tom P.. University of Oxford; Reino Unido. Future-Fit Foundation; Reino UnidoFil: Cooney, Christopher R.. University Of Sheffield; Reino UnidoFil: Hughes, Emma C.. University Of Sheffield; Reino UnidoFil: Capp, Elliot J. R.. University Of Sheffield; Reino UnidoFil: Varley, Zoë K.. University Of Sheffield; Reino Unido. Natural History Museum; Reino UnidoFil: Friedman, Nicholas R.. Okinawa Institute of Science and Technology Graduate University; JapónFil: Korntheuer, Heiko. Johannes Gutenberg Universitat Mainz; AlemaniaFil: Corrales Vargas, Andrea. Universidad Nacional de Costa Rica; Costa RicaFil: García, Natalia Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentin